President Barack Obama sounded good in his second election debate with Republican challenger Mitt Romney. But he looked good, too. Watching these debates is a lesson in the power of visual communication. It is the way the rival candidates stand, smile and move, as much as their arguments, that tell us who they are.

This is why reviews of the debate that, in striving for objectivity or attempting to undermine what was a clear victory for Obama, stress its "aggression", are getting it wrong. This was an extremely confronational encounter – both men were effectively calling each other liars – but the president did not come over as unduly aggressive, because his relaxed appearance balanced his barbed words. This is why he was able to get laughs from the audience, which Romney could not achieve.

Do appearances matter in politics? Of course they do. US presidential debates were the stage on which that fact of modern public life was first made visible. In 1960, Republican candidate Richard Nixon stood against Democrat John F Kennedy; their televised debates were a disaster for Nixon. He sweated profusely and people though he looked shifty. Meanwhile, JFK … was JFK.